WASHINGTON — Crazy-sounding ideas for saving the planet are getting a serious look from top scientists, reflecting their fears about global warming and the desire for an insurance policy in case things get worse.
There's the artificial "volcano" that shoots gigatons of sulfur high into the air, the space "sunshade" made of trillions of little reflectors between Earth and sun that would slightly lower the planet's temperature, the forest of ugly artificial "trees" that would suck carbon dioxide out of the air and the "Geritol solution" in which iron dust is dumped into the ocean.
"Of course it's desperation," said Stanford University professor Stephen Schneider. "It's planetary methadone for our planetary heroin addiction. It does come out of the pessimism of any realist that says this planet can't be trusted to do the right thing."
NASA is putting the finishing touches on a report summing up some of these ideas and has spent $75,000 to map out rough details of the sunshade concept. One of the premier climate modeling centers in the United States, the National Center for Atmospheric Research, has spent the last six weeks running computer simulations of the volcano scenario and will soon turn its attention to the space umbrella idea.
And last month, billionaire Richard Branson offered a prize of $25 million to the first feasible technology to reduce carbon dioxide levels in the air.
Simon "Pete" Worden, who heads NASA's Ames Research Center at Moffett Field in Sunnyvale, Calif., says characterizations of the proposals, which represent a field called geoengineering, have ranged from "great" to "idiotic." As if to distance NASA from the issue, Worden said the agency's report would do little more than explain the range of possibilities.
Until recently scientists were reluctant to consider such concepts, and some still are. Many fear there would be unintended side effects; others worry such schemes might prevent the type of reduction in greenhouse gas emissions that scientists say is the only real way to fight global warming. The unusual approaches are not an alternative to cutting pollution, said David Keith, a professor and geoengineering researcher at Canada's University of Calgary.
Here is a look at some of the ideas:
The Geritol solution
A private company is already carrying out this plan.
Planktos Inc. of Foster City, Calif., last week launched its ship, the Weatherbird II, on a trip to the Pacific Ocean to dump 50 tons of iron dust. The iron would grow plankton, creating an algae bloom that would drink up carbon dioxide from the atmosphere.
The idea of seeding the ocean with iron to beef up a natural plankton and algae system has been tried on a small scale several times since 1990. It has both succeeded and failed.
Russ George, Planktos' chief executive, said his ship would try it on a larger scale, dumping a slurry of water and red iron dust from a hose into the sea.
The concept gained some credibility when it was mentioned in the 2001 report by the authoritative Intergovernmental Panel on Climate Change, which cited it as a possible way to attack carbon emissions.
Small experiments "showed unequivocally that there was a biological response to the addition of the iron," the climate report said. But it also warned about "the ecological consequences of large-scale fertilization of the ocean."
When Mt. Pinatubo erupted 16 years ago in the Philippines it cooled the Earth for about a year because the sulfate particles in the upper atmosphere reflected some sunlight. Several leading scientists, including Nobel Laureate Paul Crutzen and the late nuclear bomb designer Edward Teller, have proposed doing the same artificially to offset global warming.
Using jet engines, cannons or balloons to get sulfates in the air, humans could reduce the amount of solar heat felt on earth while increasing sulfur pollution by only a small percentage, said Tom Wigley of the National Center for Atmospheric Research.
Scientists at the Center for Atmospheric Research put the idea into a computer climate model. The results aren't particularly cheap or promising, said Caspar Ammann, a scientist at the center. It would require the injection of tens of thousands of tons of sulfate into the air each month, he said.
"From a practical point of view, it's completely ridiculous," Amman said. "Instead of investing so much into this, it would be much easier to cut down on the initial problem."
For far-out concepts, it's hard to beat Roger Angel's. Last fall, the University of Arizona astronomer proposed what he called a sunshade. It would be a cloud between Earth and the sun of small Frisbee-like spaceships that would act as an umbrella, reducing heat from the sun.
The science for the ships, the rocketry to launch them, and the materials to make the shade are all doable, Angel said. The discs would each weigh less than an ounce.
About 800,000 of these would be stacked into each rocket launch. It would take 16 trillion of them, so there would be 20 million rocket launches required. The cost: at least $4 trillion over 30 years, probably more.
Scientifically, it's known as "air capture." But the proposed instruments have been dubbed "artificial trees," even though these devices are about as treelike as a radiator on a stick.
Nearly a decade ago, Columbia University professor Klaus Lackner, hit on an idea for his then-middle school daughter's science fair project: Create filters that grab carbon dioxide from the air and then compress it into a liquid or compressed gas that can be shipped elsewhere. When his daughter was able to do it on a tiny scale, Lackner decided to look at doing it globally.